[SYCL] Add support for free function kernel builtins (#15938)

Support for the following three builtins are added:
__builtin_sycl_is_single_task_kernel(function-pointer)
__builtin_sycl_is_nd_range_kernel(function-pointer, dimension)
__builtin_sycl_is_kernel(function-pointer)

__builtin_sycl_is_single_task_kernel returns true if the function
pointer represents a function with the IR attribute
"sycl-single-task-kernel".

__builtin_sycl_is_nd_range_kernel returns true if the function pointer
represents a function with the IR attribute "sycl-single-task-kernel"
with a matching dimension.

__builtin_sycl_is_kernel returns true if the function pointer represents
a function with either of the two IR attributes.

Author: premanandrao

clang/include/clang/Basic/Builtins.h

@@ -43,6 +43,7 @@ enum LanguageID : uint16_t {
   OCL_DSE = 0x400,           // builtin requires OpenCL device side enqueue.
   ALL_OCL_LANGUAGES = 0x800, // builtin for OCL languages.
   HLSL_LANG = 0x1000,        // builtin requires HLSL.
+  SYCL_LANG = 0x2000,        // builtin requires SYCL.
   ALL_LANGUAGES = C_LANG | CXX_LANG | OBJC_LANG, // builtin for all languages.
   ALL_GNU_LANGUAGES = ALL_LANGUAGES | GNU_LANG,  // builtin requires GNU mode.
   ALL_MS_LANGUAGES = ALL_LANGUAGES | MS_LANG     // builtin requires MS mode.

clang/include/clang/Basic/Builtins.td

@@ -4731,6 +4731,25 @@ def GetDeviceSideMangledName : LangBuiltin<"CUDA_LANG"> {
   let Prototype = "char const*(...)";
 }
 
+// SYCL
+def SYCLIsKernel : LangBuiltin<"SYCL_LANG"> {
+  let Spellings = ["__builtin_sycl_is_kernel"];
+  let Attributes = [NoThrow, Const, Constexpr, CustomTypeChecking];
+  let Prototype = "bool(...)";
+}
+
+def SYCLIsSingleTaskKernel : LangBuiltin<"SYCL_LANG"> {
+  let Spellings = ["__builtin_sycl_is_single_task_kernel"];
+  let Attributes = [NoThrow, Const, Constexpr, CustomTypeChecking];
+  let Prototype = "bool(...)";
+}
+
+def SYCLIsNDRangeKernel : LangBuiltin<"SYCL_LANG"> {
+  let Spellings = ["__builtin_sycl_is_nd_range_kernel"];
+  let Attributes = [NoThrow, Const, Constexpr, CustomTypeChecking];
+  let Prototype = "bool(...)";
+}
+
 // HLSL
 def HLSLAll : LangBuiltin<"HLSL_LANG"> {
   let Spellings = ["__builtin_hlsl_all"];

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -827,6 +827,9 @@ def warn_unreachable_association : Warning<
   InGroup<UnreachableCodeGenericAssoc>;
 
 /// Built-in functions.
+def err_builtin_invalid_argument_count : Error<
+  "builtin %plural{0:takes no arguments|1:takes one argument|"
+  ":requires exactly %0 arguments}0">;
 def ext_implicit_lib_function_decl : ExtWarn<
   "implicitly declaring library function '%0' with type %1">,
   InGroup<ImplicitFunctionDeclare>;
@@ -12397,7 +12400,11 @@ def err_builtin_invalid_arg_type: Error <
   "a vector of integers|"
   "an unsigned integer|"
   "an 'int'|"
-  "a vector of floating points}1 (was %2)">;
+  "a vector of floating points|"
+  "a function pointer}1 (was %2)">;
+
+def err_builtin_invalid_arg_value: Error<
+  "%ordinal0 argument must be a strictly positive value (was %1)">;
 
 def err_builtin_matrix_disabled: Error<
   "matrix types extension is disabled. Pass -fenable-matrix to enable it">;

clang/lib/AST/ExprConstant.cpp

@@ -12729,6 +12729,45 @@ static bool getBuiltinAlignArguments(const CallExpr *E, EvalInfo &Info,
   return true;
 }
 
+static bool isSYCLFreeFunctionKernel(IntExprEvaluator &IEV,
+                                     const EvalInfo &Info, const CallExpr *E,
+                                     StringRef NameStr1, StringRef NameStr2,
+                                     bool CheckNDRangeKernelDim = false) {
+  const Expr *ArgExpr = E->getArg(0)->IgnoreParenImpCasts();
+  while (isa<CastExpr>(ArgExpr))
+    ArgExpr = cast<CastExpr>(ArgExpr)->getSubExpr();
+  auto *DRE = dyn_cast<DeclRefExpr>(ArgExpr);
+  if (DRE) {
+    const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl());
+    if (FD) {
+      auto *SAIRAttr = FD->getAttr<SYCLAddIRAttributesFunctionAttr>();
+      if (!SAIRAttr)
+        return IEV.Success(false, E);
+      SmallVector<std::pair<std::string, std::string>, 4> NameValuePairs =
+          SAIRAttr->getFilteredAttributeNameValuePairs(Info.Ctx);
+      for (const auto &NVPair : NameValuePairs) {
+        if (!NVPair.first.compare(NameStr1) ||
+            (!NameStr2.empty() && !NVPair.first.compare(NameStr2))) {
+          if (CheckNDRangeKernelDim) {
+            uint64_t Dim =
+                E->getArg(1)->EvaluateKnownConstInt(Info.Ctx).getZExtValue();
+            // Return true only if the dimensions match.
+            if (std::stoul(NVPair.second) == Dim)
+              return IEV.Success(true, E);
+            else
+              return IEV.Success(false, E);
+          }
+          // Return true if it has the sycl-single-task-kernel or the
+          // sycl-nd-range-kernel attribute.
+          return IEV.Success(true, E);
+        }
+      }
+      return IEV.Success(false, E);
+    }
+  }
+  return false;
+}
+
 bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
                                             unsigned BuiltinOp) {
   switch (BuiltinOp) {
@@ -13674,6 +13713,19 @@ bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
         Result.setBitVal(P++, Val[I]);
     return Success(Result, E);
   }
+
+  case Builtin::BI__builtin_sycl_is_kernel: {
+    return isSYCLFreeFunctionKernel(*this, Info, E, "sycl-single-task-kernel",
+                                    "sycl-nd-range-kernel");
+  }
+  case Builtin::BI__builtin_sycl_is_single_task_kernel: {
+    return isSYCLFreeFunctionKernel(*this, Info, E, "sycl-single-task-kernel",
+                                    "");
+  }
+  case Builtin::BI__builtin_sycl_is_nd_range_kernel: {
+    return isSYCLFreeFunctionKernel(*this, Info, E, "sycl-nd-range-kernel", "",
+                                    /*CheckNDRangeDim=*/true);
+  }
   }
 }
 

clang/lib/Basic/Builtins.cpp

@@ -119,6 +119,9 @@ static bool builtinIsSupported(const Builtin::Info &BuiltinInfo,
   /* CUDA Unsupported */
   if (!LangOpts.CUDA && BuiltinInfo.Langs == CUDA_LANG)
     return false;
+  /* SYCL Unsupported */
+  if (!LangOpts.isSYCL() && BuiltinInfo.Langs == SYCL_LANG)
+    return false;
   /* CPlusPlus Unsupported */
   if (!LangOpts.CPlusPlus && BuiltinInfo.Langs == CXX_LANG)
     return false;

clang/lib/CodeGen/CGBuiltin.cpp

@@ -2716,6 +2716,53 @@ static RValue EmitHipStdParUnsupportedBuiltin(CodeGenFunction *CGF,
   return RValue::get(CGF->Builder.CreateCall(UBF, Args));
 }
 
+static RValue EmitSYCLFreeFunctionKernelBuiltin(CodeGenFunction &CGF,
+                                                const CallExpr *E,
+                                                StringRef NameStr1,
+                                                StringRef NameStr2,
+                                                bool CheckNDRangeDim = false) {
+  const Expr *ArgExpr = E->getArg(0)->IgnoreImpCasts();
+  auto *UO = dyn_cast<clang::UnaryOperator>(ArgExpr);
+  // If this is of the form &function or *function, get to the function
+  // sub-expression.
+  if (UO && (UO->getOpcode() == UO_AddrOf || UO->getOpcode() == UO_Deref))
+    ArgExpr = UO->getSubExpr()->IgnoreParenImpCasts();
+  while (isa<CastExpr>(ArgExpr))
+    ArgExpr = cast<CastExpr>(ArgExpr)->getSubExpr();
+  auto *DRE = dyn_cast<DeclRefExpr>(ArgExpr);
+  if (DRE) {
+    const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl());
+    if (FD && FD->hasAttr<SYCLAddIRAttributesFunctionAttr>()) {
+      auto *SAIRAttr = FD->getAttr<SYCLAddIRAttributesFunctionAttr>();
+      SmallVector<std::pair<std::string, std::string>, 4> NameValuePairs =
+          SAIRAttr->getFilteredAttributeNameValuePairs(CGF.CGM.getContext());
+      for (const auto &NVPair : NameValuePairs) {
+        if (!NVPair.first.compare(NameStr1) ||
+            (!NameStr2.empty() && !!NVPair.first.compare(NameStr2))) {
+          if (CheckNDRangeDim) {
+            uint64_t Dim = E->getArg(1)
+                               ->EvaluateKnownConstInt(CGF.CGM.getContext())
+                               .getZExtValue();
+            // Return true only if the dimensions match.
+            if (std::stoul(NVPair.second) == Dim)
+              return RValue::get(
+                  llvm::ConstantInt::getTrue(CGF.ConvertType(E->getType())));
+            else
+              return RValue::get(
+                  llvm::ConstantInt::getFalse(CGF.ConvertType(E->getType())));
+          }
+          // Return true if the kernel type matches.
+          return RValue::get(
+              llvm::ConstantInt::getTrue(CGF.ConvertType(E->getType())));
+        }
+      }
+    }
+  }
+  // Return false otherwise.
+  return RValue::get(
+      llvm::ConstantInt::getFalse(CGF.ConvertType(E->getType())));
+}
+
 RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
                                         const CallExpr *E,
                                         ReturnValueSlot ReturnValue) {
@@ -6363,6 +6410,18 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
     auto Str = CGM.GetAddrOfConstantCString(Name, "");
     return RValue::get(Str.getPointer());
   }
+  case Builtin::BI__builtin_sycl_is_kernel: {
+    return EmitSYCLFreeFunctionKernelBuiltin(
+        *this, E, "sycl-single-task-kernel", "sycl-nd-range-kernel");
+  }
+  case Builtin::BI__builtin_sycl_is_single_task_kernel: {
+    return EmitSYCLFreeFunctionKernelBuiltin(*this, E,
+                                             "sycl-single-task-kernel", "");
+  }
+  case Builtin::BI__builtin_sycl_is_nd_range_kernel: {
+    return EmitSYCLFreeFunctionKernelBuiltin(*this, E, "sycl-nd-range-kernel",
+                                             "", /*CheckNDRangeDim=*/true);
+  }
   }
 
   // If this is an alias for a lib function (e.g. __builtin_sin), emit

clang/lib/Sema/SemaChecking.cpp

@@ -3026,6 +3026,40 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
     }
     break;
   }
+
+  case Builtin::BI__builtin_sycl_is_kernel:
+  case Builtin::BI__builtin_sycl_is_single_task_kernel:
+  case Builtin::BI__builtin_sycl_is_nd_range_kernel: {
+    unsigned int ExpNumArgs =
+        BuiltinID == Builtin::BI__builtin_sycl_is_nd_range_kernel ? 2 : 1;
+    // Builtin takes either 1 or 2 arguments.
+    if (TheCall->getNumArgs() != ExpNumArgs) {
+      Diag(TheCall->getBeginLoc(), diag::err_builtin_invalid_argument_count)
+          << ExpNumArgs;
+      return ExprError();
+    }
+
+    const Expr *Arg = TheCall->getArg(0);
+    QualType ArgTy = Arg->getType();
+
+    if (!ArgTy->isFunctionProtoType() && !ArgTy->isFunctionPointerType()) {
+      Diag(Arg->getBeginLoc(), diag::err_builtin_invalid_arg_type)
+          << 1 << /* pointer to function type */ 10 << ArgTy;
+      return ExprError();
+    }
+
+    if (ExpNumArgs == 2) {
+      int64_t DimArg =
+          TheCall->getArg(1)->EvaluateKnownConstInt(Context).getSExtValue();
+      if (DimArg <= 0) {
+        Diag(Arg->getBeginLoc(), diag::err_builtin_invalid_arg_value)
+            << 2 << DimArg;
+        return ExprError();
+      }
+    }
+
+    break;
+  }
   }
 
   if (getLangOpts().HLSL && HLSL().CheckBuiltinFunctionCall(BuiltinID, TheCall))

clang/test/CodeGenSYCL/builtin_sycl_kernel.cpp

@@ -0,0 +1,79 @@
+// RUN: %clang_cc1 -internal-isystem %S/Inputs -fsycl-is-device -triple spir64-unknown-unknown -disable-llvm-passes -emit-llvm %s -o - | FileCheck %s
+
+// This test tests the builtin __builtin_sycl_is_kernel
+
+#include "sycl.hpp"
+
+using namespace sycl;
+queue q;
+
+__attribute__((sycl_device))
+[[__sycl_detail__::add_ir_attributes_function("sycl-single-task-kernel", 0)]]
+void sstk_free_func() {
+}
+
+template <typename T>
+[[__sycl_detail__::add_ir_attributes_function("sycl-single-task-kernel", 4)]]
+void sstk_free_func_tmpl(T *ptr) {
+  for (int i = 0; i <= 7; i++)
+    ptr[i] = i + 11;
+}
+
+__attribute__((sycl_device))
+[[__sycl_detail__::add_ir_attributes_function("sycl-single-task-kernel", 1)]]
+void ovl_free_func(int *ptr) {
+  for (int i = 0; i <= 7; i++)
+    ptr[i] = i;
+}
+
+__attribute__((sycl_device))
+[[__sycl_detail__::add_ir_attributes_function("sycl-nd-range-kernel", 1)]]
+void ovl_free_func(int *ptr, int val) {
+  for (int i = 0; i <= 7; i++)
+    ptr[i] = i + val;
+}
+
+__attribute__((sycl_device))
+[[__sycl_detail__::add_ir_attributes_function("sycl-nd-range-kernel", 4)]]
+void sndrk_free_func() {
+}
+
+void func() {}
+
+void foo() {
+  bool b1 = __builtin_sycl_is_kernel(sstk_free_func);
+  // CHECK: store i8 1, ptr addrspace(4) %b1{{.*}}, align 1
+  bool b2 = __builtin_sycl_is_kernel(*sstk_free_func);
+  // CHECK: store i8 1, ptr addrspace(4) %b2{{.*}}, align 1
+  bool b3 = __builtin_sycl_is_kernel(&sstk_free_func);
+  // CHECK: store i8 1, ptr addrspace(4) %b3{{.*}}, align 1
+  bool b4 = __builtin_sycl_is_kernel(func);
+  // CHECK: store i8 0, ptr addrspace(4) %b4{{.*}}, align 1
+  bool b5 = __builtin_sycl_is_kernel(sndrk_free_func);
+  // CHECK: store i8 1, ptr addrspace(4) %b5{{.*}}, align 1
+
+  // Constexpr forms of the valid cases.
+  constexpr bool b6 = __builtin_sycl_is_kernel(sstk_free_func);   // Okay and true.
+  // CHECK: store i8 1, ptr addrspace(4) %b6{{.*}}, align 1
+  constexpr bool b7 = __builtin_sycl_is_kernel(func);   // Okay, but false.
+  // CHECK: store i8 0, ptr addrspace(4) %b7{{.*}}, align 1
+  constexpr bool b8 = __builtin_sycl_is_kernel(sndrk_free_func);   // Okay, but false.
+  // CHECK: store i8 1, ptr addrspace(4) %b8{{.*}}, align 1
+
+  // Test function template.
+  constexpr bool b9 = __builtin_sycl_is_kernel((void(*)(int *))sstk_free_func_tmpl<int>);  // Okay
+  // CHECK: store i8 1, ptr addrspace(4) %b9{{.*}}, align 1
+
+  // Test overloaded functions.
+  constexpr bool b10 = __builtin_sycl_is_kernel((void(*)(int *))ovl_free_func);  // Okay
+  // CHECK: store i8 1, ptr addrspace(4) %b10{{.*}}, align 1
+  constexpr bool b11 = __builtin_sycl_is_kernel((void(*)(int *, int))ovl_free_func);  // Okay
+  // CHECK: store i8 1, ptr addrspace(4) %b11{{.*}}, align 1
+}
+
+void f() {
+  auto L = []() { foo(); };
+  q.submit([&](handler &h) {
+    h.single_task<class kernel_name_1>(L);
+  });
+}